Let's start with the good stuff. Britain is one of the most liberal, most tolerant countries in the world. Given the challenges it faces from diverse, ever-changing communities in the major conurbations, it manages its affairs with a remarkable degree of harmony. We live, indigenous and non-indigenous, in relative proximity. Generally speaking, we don't much like extremism or extremists. For less good examples, look to bits of Europe that don't cope so well: look at France, look at Germany; look at Italy. No, don't look at Italy – well, not directly. The soul can only take so much horror.

But for all that, something is happening, and it isn't good. We're drifting back. Hard to gauge these things exactly, but look at the web postings, listen to the radio phone-ins, read the newspapers, cup an ear outside a playground. Talk to young black men or Muslims about their recent experiences with the police; go to Dale Farm and talk to the Travellers facing eviction; witness how sexual attention towards women frequently escalates into aggression and obscenities when young men are rebuffed.

Things are not "disgusting", as the American singer Kelis pronounced this week, but we do seem to be moving towards a new normal. Britain feels that bit harsher, a little bit meaner, less considerate; indeed, the opposite of everything the prime minister promises in his "big society". The inevitable consequence, you say, of a society facing unemployment, contraction, scarcity and recession. Perhaps. But I don't think we are here by accident. This is a course that was set.

A remarkable thing happened in 1999 in the aftermath of the death of the black teenager Stephen Lawrence. Pretty much against the advice of Tony Blair, Jack Straw set up the Macpherson inquiry. It was a judicial investigation that prodded and probed the workings of the Metropolitan police; but more importantly it also had a hard look at our institutions.

As it pulled away at the many layers, we saw we had become accustomed to levels of discriminatory behaviour that did us no credit. The police, as always, took the first hit, but their failings were merely the failings of our society in microcosm: the racism, the sexism; the distaste for, and often hostility to, difference; the arrogance that characterised encounters between those in the majority endowed with authority, and those of a different race and gender and social background who had none.

Macpherson made us look again at it all. And we were the better for it. But we didn't all feel better. Sections of the police hated Macpherson because they lost the ability to offend who they pleased, to stop who they wanted, and had to talk to the minorities they felt they should have been policing. By the time the ripples spread to the NHS, the civil service and private firms terrified of being exposed for being out of step in terms of equalities, Macpherson gained more enemies. Those who have power don't surrender it easily.

The "ludicrous Macpherson report of 1999", wrote Peter Hitchens in one of his many assaults. A "sub-marxist analysis of the institutions of contemporary Britain", railed the Express's Leo McKinstry. It's all a "McCarthyite witch hunt spawned by Stephen's death", said the Mail's Richard Littlejohn. Yes, it spawned "a kind of McCarthyism," added his colleague Melanie Phillips. We're too politically correct, says the much-quoted Campaign Against Political Correctness. We're wasting money, says the TaxPayers' Alliance. They articulate the backlash.

Over time, the kickback has worked. When it emerges that once again some school pupils, no doubt echoing their parents, throw words such as Jew and gay and Paki and Chink around like so much plasticine, the reaction from the Mail and the Express is to criticise the teachers who make a note of it. When the Dale Farm Travellers say they are being unfairly treated and refuse to move, the Sun suggests the council should "let the locals loose on the site". When community advisers exercise their policing function in Tottenham, as envisaged by Macpherson, and warn tensions are high after the shooting of Mark Duggan, those warnings go unheeded, for once again they are no longer seen as people worth listening to. Next stop, riot shields.

There was a healthier mindset for a decade after Macpherson, but there was never buy-in from the establishment – the politicians, the mandarins and the media moguls – and so those changes were never woven into the fabric. The right huffed and puffed and lobbied about political correctness gone mad. And they got what they wanted. This is the post-Macpherson world they wanted, and it's meaner and harsher and less equitable and more divisive. This is a creature of their design; they may as well celebrate it. And if just occasionally they have to suffer its ill-effects, they really shouldn't complain.